When it comes to suspended timber floors, the main heat loss culprit is convection heat loss (aka draughts, air leakage) and not conduction (which insulation addresses). Therefore a hugely effective (and relative cheaper) measure to consider without huge disruption internally is to seal the floor from wall to wall with an air tightness membrane (the current floor covering would need to be temporarily removed or replaced). This prevents the cooler outside air from coming up uncontrolled through the floor (or visa versa with warm internal air being lost through it) and does not change the ffl generally.
Doing this alone throughout the house could have quite a large impact in the overall heat loss equation.
FWIW most wooden floor underlays act as a moisture barrier and are airtight. You just need to use a decent air tightness tape to join the sheets and attach them to the walls, ideally behind the skirting to keep it all in-place.any reason you couldn't put the membrane on top of the existing boards, then a floating floor on top with an insulated underlay?
Spec we got was to do weather tight membrane, stapled to joists, then insulation, then airtight membrane. I don't believe that anything above floor would have the same impact.That's what I thought Mick'r. By the way, do you know if there are any effective above-timber floor insulation methods. Read about Floor foam but not sure of it's efectiveness.
Much more limited set available for individual energy upgradesDoes splitting the tasks exclude people from the so called grant?
You might be able to achieve air-tightness as they were suggesting, but those underlays have negligible insulation value.I don't believe that anything above floor would have the same impact.
You might be able to achieve air-tightness as they were suggesting, but those underlays have negligible insulation value.
It matters around 10-20%, as that's the typical range of heat loss through an uninsulated floor but you're right that draughts are often a bigger concern. I was really pointing it out as some try to oversell underlay or similar membranes as having significant insulation properties.How much does it really matter though - I think draughts are the biggest problem. Wood has reasonable insulation properties. I've used an infrared thermometer in my draughty office with a bare suspended floor - the floor itself is slightly colder than the (somewhat insulated) walls, but the area around the skirting is much colder due to air leaking in around the edges. I've noticed the window frames are also several degrees colder (double glazed but probably 20 years old).